/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.huanxinapi.videoutil;

import java.io.File;
import java.lang.ref.SoftReference;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.util.LruCache;
import android.util.Log;

import com.huanxinapi.activity.BuildConfig;
import com.huanxinapi.videoutil.RecyclingBitmapDrawable;
import com.huanxinapi.videoutil.Utils;


/**
 * This class memory caching of bitmaps in conjunction with the
 * {@link ImageCache#getInstance(android.support.v4.app.FragmentManager, ImageCacheParams)}
 * to get an instance of this class, although usually a cache should be added
 * .
 */
public class ImageCache {
    private static final String TAG = "ImageCache";

    // Default memory cache size in kilobytes
    private static final int DEFAULT_MEM_CACHE_SIZE = 1024 * 5; // 5MB

    private static final int DEFAULT_COMPRESS_QUALITY = 70;

    // Constants to easily toggle various caches
    private static final boolean DEFAULT_MEM_CACHE_ENABLED = true;
    private static final boolean DEFAULT_INIT_DISK_CACHE_ON_CREATE = false;

    private LruCache<String, BitmapDrawable> mMemoryCache;
    private ImageCacheParams mCacheParams;

    private Set<SoftReference<Bitmap>> mReusableBitmaps;

    /**
     * Create a new ImageCache object using the specified parameters. This
     * should not be called directly by other classes, instead use
     * {@link ImageCache#getInstance(android.support.v4.app.FragmentManager, ImageCacheParams)}
     * to fetch an ImageCache instance.
     *
     * @param cacheParams
     *            The cache parameters to use to initialize the cache
     */
    private ImageCache(ImageCacheParams cacheParams) {
        init(cacheParams);
    }

    /**
     * Return an {@link ImageCache} instance. A {@link RetainFragment} is used
     * to retain the ImageCache object across configuration changes such as a
     * change in device orientation.
     *
     * @param fragmentManager
     *            The fragment manager to use when dealing with the retained
     *            fragment.
     * @param cacheParams
     *            The cache parameters to use if the ImageCache needs
     *            instantiation.
     * @return An existing retained ImageCache object or a new one if one did
     *         not exist
     */
    public static ImageCache getInstance(FragmentManager fragmentManager,
                                         ImageCacheParams cacheParams) {

        // Search for, or create an instance of the non-UI RetainFragment
        final RetainFragment mRetainFragment = findOrCreateRetainFragment(fragmentManager);

        // See if we already have an ImageCache stored in RetainFragment
        ImageCache imageCache = (ImageCache) mRetainFragment.getObject();

        // No existing ImageCache, create one and store it in RetainFragment
        if (imageCache == null) {
            imageCache = new ImageCache(cacheParams);
            mRetainFragment.setObject(imageCache);
        }

        return imageCache;
    }

    /**
     * Initialize the cache, providing all parameters.
     *
     * @param cacheParams
     *            The cache parameters to initialize the cache
     */
    private void init(ImageCacheParams cacheParams) {
        mCacheParams = cacheParams;

        // BEGIN_INCLUDE(init_memory_cache)
        // Set up memory cache
        if (mCacheParams.memoryCacheEnabled) {
            if (BuildConfig.DEBUG) {
                Log.d(TAG, "Memory cache created (size = "
                        + mCacheParams.memCacheSize + ")");
            }

            // If we're running on Honeycomb or newer, create a set of reusable
            // bitmaps that can be
            // populated into the inBitmap field of BitmapFactory.Options. Note
            // that the set is
            // of SoftReferences which will actually not be very effective due
            // to the garbage
            // collector being aggressive clearing Soft/WeakReferences. A better
            // approach
            // would be to use a strongly references bitmaps, however this would
            // require some
            // balancing of memory usage between this set and the bitmap
            // LruCache. It would also
            // require knowledge of the expected size of the bitmaps. From
            // Honeycomb to JellyBean
            // the size would need to be precise, from KitKat onward the size
            // would just need to
            // be the upper bound (due to changes in how inBitmap can re-use
            // bitmaps).
            if (Utils.hasHoneycomb()) {
                mReusableBitmaps = Collections
                        .synchronizedSet(new HashSet<SoftReference<Bitmap>>());
            }

            mMemoryCache = new LruCache<String, BitmapDrawable>(
                    mCacheParams.memCacheSize) {

                /**
                 * Notify the removed entry that is no longer being cached
                 */
                @Override
                protected void entryRemoved(boolean evicted, String key,
                                            BitmapDrawable oldValue, BitmapDrawable newValue) {
                    if (RecyclingBitmapDrawable.class.isInstance(oldValue)) {
                        // The removed entry is a recycling drawable, so notify
                        // it
                        // that it has been removed from the memory cache
                        ((RecyclingBitmapDrawable) oldValue).setIsCached(false);
                    } else {
                        // The removed entry is a standard BitmapDrawable

                        if (Utils.hasHoneycomb()) {
                            // We're running on Honeycomb or later, so add the
                            // bitmap
                            // to a SoftReference set for possible use with
                            // inBitmap later
                            mReusableBitmaps.add(new SoftReference<Bitmap>(
                                    oldValue.getBitmap()));
                        }
                    }
                }

                /**
                 * Measure item size in kilobytes rather than units which is
                 * more practical for a bitmap cache
                 */
                @Override
                protected int sizeOf(String key, BitmapDrawable value) {
                    final int bitmapSize = getBitmapSize(value) / 1024;
                    return bitmapSize == 0 ? 1 : bitmapSize;
                }
            };
        }

    }

    /**
     * Adds a bitmap to both memory and disk cache.
     *
     * @param data
     *            Unique identifier for the bitmap to store
     * @param value
     *            The bitmap drawable to store
     */
    public void addBitmapToCache(String data, BitmapDrawable value) {
        // BEGIN_INCLUDE(add_bitmap_to_cache)
        if (data == null || value == null) {
            return;
        }

        // Add to memory cache
        if (mMemoryCache != null) {
            if (RecyclingBitmapDrawable.class.isInstance(value)) {
                // The removed entry is a recycling drawable, so notify it
                // that it has been added into the memory cache
                ((RecyclingBitmapDrawable) value).setIsCached(true);
            }
            mMemoryCache.put(data, value);
        }

    }

    /**
     * Get from memory cache.
     *
     * @param data
     *            Unique identifier for which item to get
     * @return The bitmap drawable if found in cache, null otherwise
     */
    public BitmapDrawable getBitmapFromMemCache(String data) {
        // BEGIN_INCLUDE(get_bitmap_from_mem_cache)
        BitmapDrawable memValue = null;

        if (mMemoryCache != null) {
            memValue = mMemoryCache.get(data);
        }

        if (BuildConfig.DEBUG && memValue != null) {
            Log.d(TAG, "Memory cache hit");
        }

        return memValue;
        // END_INCLUDE(get_bitmap_from_mem_cache)
    }

    /**
     * @param options
     *            - BitmapFactory.Options with out* options populated
     * @return Bitmap that case be used for inBitmap
     */
    protected Bitmap getBitmapFromReusableSet(BitmapFactory.Options options) {
        // BEGIN_INCLUDE(get_bitmap_from_reusable_set)
        Bitmap bitmap = null;

        if (mReusableBitmaps != null && !mReusableBitmaps.isEmpty()) {
            synchronized (mReusableBitmaps) {
                final Iterator<SoftReference<Bitmap>> iterator = mReusableBitmaps
                        .iterator();
                Bitmap item;

                while (iterator.hasNext()) {
                    item = iterator.next().get();

                    if (null != item && item.isMutable()) {
                        // Check to see it the item can be used for inBitmap
                        if (canUseForInBitmap(item, options)) {
                            bitmap = item;

                            // Remove from reusable set so it can't be used
                            // again
                            iterator.remove();
                            break;
                        }
                    } else {
                        // Remove from the set if the reference has been
                        // cleared.
                        iterator.remove();
                    }
                }
            }
        }

        return bitmap;
        // END_INCLUDE(get_bitmap_from_reusable_set)
    }

    /**
     * Clears both the memory and disk cache associated with this ImageCache
     * object. Note that this includes disk access so this should not be
     * executed on the main/UI thread.
     */
    public void clearCache() {
        if (mMemoryCache != null) {
            mMemoryCache.evictAll();
            if (BuildConfig.DEBUG) {
                Log.d(TAG, "Memory cache cleared");
            }
        }

    }

    /**
     * A holder class that contains cache parameters.
     */
    public static class ImageCacheParams {
        public int memCacheSize = DEFAULT_MEM_CACHE_SIZE;
        public int compressQuality = DEFAULT_COMPRESS_QUALITY;
        public boolean memoryCacheEnabled = DEFAULT_MEM_CACHE_ENABLED;
        public boolean initDiskCacheOnCreate = DEFAULT_INIT_DISK_CACHE_ON_CREATE;


        /**
         * Sets the memory cache size based on a percentage of the max available
         * VM memory. Eg. setting percent to 0.2 would set the memory cache to
         * one fifth of the available memory. Throws
         * {@link IllegalArgumentException} if percent is < 0.01 or > .8.
         * memCacheSize is stored in kilobytes instead of bytes as this will
         * eventually be passed to construct a LruCache which takes an int in
         * its constructor.
         *
         * This value should be chosen carefully based on a number of factors
         * Refer to the corresponding Android Training class for more
         * discussion: http://developer.android.com/training/displaying-bitmaps/
         *
         * @param percent
         *            Percent of available app memory to use to size memory
         *            cache
         */
        public void setMemCacheSizePercent(float percent) {
            if (percent < 0.01f || percent > 0.8f) {
                throw new IllegalArgumentException(
                        "setMemCacheSizePercent - percent must be "
                                + "between 0.01 and 0.8 (inclusive)");
            }
            memCacheSize = Math.round(percent
                    * Runtime.getRuntime().maxMemory() / 1024);
        }
    }

    /**
     * @param candidate
     *            - Bitmap to check
     * @param targetOptions
     *            - Options that have the out* value populated
     * @return true if <code>candidate</code> can be used for inBitmap re-use
     *         with <code>targetOptions</code>
     */
    @TargetApi(19)
    private static boolean canUseForInBitmap(Bitmap candidate,
                                             BitmapFactory.Options targetOptions) {
        // BEGIN_INCLUDE(can_use_for_inbitmap)
        if (!Utils.hasKitKat()) {
            // On earlier versions, the dimensions must match exactly and the
            // inSampleSize must be 1
            return candidate.getWidth() == targetOptions.outWidth
                    && candidate.getHeight() == targetOptions.outHeight
                    && targetOptions.inSampleSize == 1;
        }

        // From Android 4.4 (KitKat) onward we can re-use if the byte size of
        // the new bitmap
        // is smaller than the reusable bitmap candidate allocation byte count.
        int width = targetOptions.outWidth / targetOptions.inSampleSize;
        int height = targetOptions.outHeight / targetOptions.inSampleSize;
        int byteCount = width * height
                * getBytesPerPixel(candidate.getConfig());
        return byteCount <= candidate.getByteCount();
        // END_INCLUDE(can_use_for_inbitmap)
    }

    /**
     * Return the byte usage per pixel of a bitmap based on its configuration.
     *
     * @param config
     *            The bitmap configuration.
     * @return The byte usage per pixel.
     */
    private static int getBytesPerPixel(Config config) {
        if (config == Config.ARGB_8888) {
            return 4;
        } else if (config == Config.RGB_565) {
            return 2;
        } else if (config == Config.ARGB_4444) {
            return 2;
        } else if (config == Config.ALPHA_8) {
            return 1;
        }
        return 1;
    }

    /**
     * Get a usable cache directory (external if available, internal otherwise).
     *
     * @param context
     *            The context to use
     * @param uniqueName
     *            A unique directory name to append to the cache dir
     * @return The cache dir
     */
    public static File getDiskCacheDir(Context context, String uniqueName) {
        // Check if media is mounted or storage is built-in, if so, try and use
        // external cache dir
        // otherwise use internal cache dir
        final String cachePath = Environment.MEDIA_MOUNTED.equals(Environment
                .getExternalStorageState()) || !isExternalStorageRemovable() ? getExternalCacheDir(
                context).getPath()
                : context.getCacheDir().getPath();

        return new File(cachePath + File.separator + uniqueName);
    }

    /**
     * A hashing method that changes a string (like a URL) into a hash suitable
     * for using as a disk filename.
     */
    public static String hashKeyForDisk(String key) {
        String cacheKey;
        try {
            final MessageDigest mDigest = MessageDigest.getInstance("MD5");
            mDigest.update(key.getBytes());
            cacheKey = bytesToHexString(mDigest.digest());
        } catch (NoSuchAlgorithmException e) {
            cacheKey = String.valueOf(key.hashCode());
        }
        return cacheKey;
    }

    private static String bytesToHexString(byte[] bytes) {
        // http://stackoverflow.com/questions/332079
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(0xFF & bytes[i]);
            if (hex.length() == 1) {
                sb.append('0');
            }
            sb.append(hex);
        }
        return sb.toString();
    }

    /**
     * Get the size in bytes of a bitmap in a BitmapDrawable. Note that from
     * Android 4.4 (KitKat) onward this returns the allocated memory size of the
     * bitmap which can be larger than the actual bitmap data byte count (in the
     * case it was re-used).
     *
     * @param value
     * @return size in bytes
     */
    @TargetApi(19)
    public static int getBitmapSize(BitmapDrawable value) {
        Bitmap bitmap = value.getBitmap();

        // From KitKat onward use getAllocationByteCount() as allocated bytes
        // can potentially be
        // larger than bitmap byte count.
//		if (Utils.hasKitKat()) {
//			return bitmap.getAllocationByteCount();
//		}

        if (Utils.hasHoneycombMR1()) {
            return bitmap.getByteCount();
        }

        // Pre HC-MR1
        return bitmap.getRowBytes() * bitmap.getHeight();
    }

    /**
     * Check if external storage is built-in or removable.
     *
     * @return True if external storage is removable (like an SD card), false
     *         otherwise.
     */
    @TargetApi(VERSION_CODES.GINGERBREAD)
    public static boolean isExternalStorageRemovable() {
        if (Utils.hasGingerbread()) {
            return Environment.isExternalStorageRemovable();
        }
        return true;
    }

    /**
     * Get the external app cache directory.
     *
     * @param context
     *            The context to use
     * @return The external cache dir
     */
    @TargetApi(VERSION_CODES.FROYO)
    public static File getExternalCacheDir(Context context) {
        if (Utils.hasFroyo()) {
            return context.getExternalCacheDir();
        }

        // Before Froyo we need to construct the external cache dir ourselves
        final String cacheDir = "/Android/data/" + context.getPackageName()
                + "/cache/";
        return new File(Environment.getExternalStorageDirectory().getPath()
                + cacheDir);
    }

    /**
     * Locate an existing instance of this Fragment or if not found, create and
     * add it using FragmentManager.
     *
     * @param fm
     *            The FragmentManager manager to use.
     * @return The existing instance of the Fragment or the new instance if just
     *         created.
     */
    private static RetainFragment findOrCreateRetainFragment(FragmentManager fm) {
        // BEGIN_INCLUDE(find_create_retain_fragment)
        // Check to see if we have retained the worker fragment.
        RetainFragment mRetainFragment = (RetainFragment) fm
                .findFragmentByTag(TAG);

        // If not retained (or first time running), we need to create and add
        // it.
        if (mRetainFragment == null) {
            mRetainFragment = new RetainFragment();
            fm.beginTransaction().add(mRetainFragment, TAG)
                    .commitAllowingStateLoss();
        }

        return mRetainFragment;
        // END_INCLUDE(find_create_retain_fragment)
    }

    /**
     * A simple non-UI Fragment that stores a single Object and is retained over
     * configuration changes. It will be used to retain the ImageCache object.
     */
    public static class RetainFragment extends Fragment {
        private Object mObject;

        /**
         * Empty constructor as per the Fragment documentation
         */
        public RetainFragment() {
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            // Make sure this Fragment is retained over a configuration change
            setRetainInstance(true);
        }

        /**
         * Store a single object in this Fragment.
         *
         * @param object
         *            The object to store
         */
        public void setObject(Object object) {
            mObject = object;
        }

        /**
         * Get the stored object.
         *
         * @return The stored object
         */
        public Object getObject() {
            return mObject;
        }
    }

}
